Field of the Invention
The invention relates to a proximity service (ProSe) technique, and more particularly, to a method of message retransmission for a discovery procedure of the proximity service and a user equipment using the same.
Description of Related Art
In recent years, with rapid development in mobile communication technologies and smart handheld devices, global mobile broadband users and mobile data traffics both show an exponential growth. However, the exploding amounts of mobile broadband users and data traffics lead to issues regarding spectral efficiency, frequency utilization and network coverage of mobile communication network. Accordingly, in next generation wireless communication technologies (e.g., 4G, 5G) of Third Generation Partnership Project (3GPP), solutions and technical discussions have been proposed specifically for aforementioned issues. As a result, a device-to-device (D2D) communication technology has become one of focused technologies in development.
In a traditional mobile communication network, a user equipment (UE) such as a smart phone, a tablet computer and the like needs to transmit voice or data signals through a core network. The D2D technology brings innovative business value to telecommunication operators by forwarding data through use of proximity device discovery and direct communication instead of going through the core network thereby achieving effectiveness of offload, Location-Based Service (LBS) and the like.